A display device which is worn on a head for viewing images, in other words, a head-mount display (HMD), has been widely known. Such a head-mount display is configured to have optical units each for the left and right eyes, and to be able to control the senses of viewing and hearing by also using a headphone. If such a device is configured to completely block the outside world when mounted on a head, a feeling of virtual reality during viewing increases. In addition, as a head-mount display can also project different images to the right and left eyes, 3D images can be presented when images having parallax are displayed for the right and left eyes.
For a display unit of a head-mount display for the right and left eyes, high-definition display panels which include, for example, liquid crystal or organic EL (Electro-Luminescence) elements, or the like can be used. In addition, if a wide angle of view is set by enlarging and projecting image display elements with an eyepiece optical system, and multi-channels are realized using a headphone, a rich feeling of presence in a movie theater for viewing and listening can be reproduced.
Since there are differences among individual users in heights and intervals of eyes and a head-mount display has independent eyepiece optical systems for the right and left sides, it is necessary to match the positions of the eyepiece optical systems with those of the eyes of a user wearing the device. Since large screens are projected in front of the eyes, when reproduced video images of a Blu-ray disc, or the like are watched for a long period of time, it is preferable to precisely match the position of the images projected from a head-mount display with the eye interval to keep the eyes healthy.
For example, a head-mount display which has an eye interval adjusting mechanism using a rack-and-pinion method in response to differences between individual users has been proposed (for example, refer to Patent Literature 1). In addition, a head-mount display which has a rotary shaft between a left-eye display unit and a right-eye display unit is provided with a rotary member that is connected to each of the display units via arms, and includes an eye interval adjusting mechanism that adjusts the distance between the left-eye display unit and the right-eye display unit so as to be symmetric on the right and left sides by rotating the rotary member has been proposed (for example, refer to Patent Literature 2).
In addition, the specification of Japanese Patent Application No. 2010-287835 (Patent Literature 3), which has already been transferred to the present applicant, proposes a head-mount display which can precisely adjust an eye interval with a direct operation of an eye interval adjusting mechanism by a user wearing the device. Since this head-mount display displays a signal pattern for eye interval adjustment while the eye interval is adjusted, the user can more precisely adjust the eye interval by operating the eye interval adjusting mechanism by himself or herself while observing the signal pattern.
When the lens centers of eyepiece optical systems do not match the center positions of the eyes, the mismatch causes a part or all of a displayed image to appear distorted, or each of R, G, and B to appear shifted in a part or all of a screen due to magnification chromatic aberrations of lenses.
However, even when an eye interval adjusting mechanism is provided, it is difficult to precisely match the lens centers of the eyepiece optical systems and the center positions of the eyes. In addition, when it is not possible in the eye interval adjusting mechanism to adjust the positions with no stages, but only to fix the positions in stages, there are users for whom the eye interval is not able to be adjusted at all.
The problem of adjusting an eye interval as described above can be solved by using a lens which causes little distortion and magnification chromatic aberrations even if the lens centers do not match the center positions of the eyes. However, such a lens incurs a high manufacturing cost. In addition, since the weight of the lens becomes heavy, a feeling of wearing the head-mount display becomes worse.
Alternatively, such a problem of adjusting an eye interval can be solved by employing an eye interval adjusting mechanism which can adjust positions with no stages, but the employment causes the mechanism to be complicated, resulting in an increase in the device cost.